Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the destructiveHint annotation, the description discloses that detaching an 'owned' row leaves the referenced character untouched, while a 'link' row discards local overlay counters. It also explains the response shape and instructs the agent to adopt the returned `updatedAt`, adding valuable operational context.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is dense but every sentence earns its place: the action, the identifier caveat, the two row-type behaviors, and the response/updatedAt instruction are all operational essentials. It is well-structured and front-loaded with the primary action.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool has two fully described parameters, clear annotations, and an output schema, and the description covers the behavioral nuances and response handling. An agent has everything it needs to select and invoke this tool correctly.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is already 100%, but the description adds critical disambiguation: `companionId` is the row `_id` from `companions[]`, not the buddy character's id, and should be sourced from vault_get_character. This prevents a highly plausible misuse that the schema alone might not fully communicate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Remove') and resource ('companion row from a Main character's sheet') and clarifies the exact identifier by which removal happens. It clearly differentiates from related vault operations by specifying the row `_id` rather than a character id.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description gives clear context for when this tool applies by distinguishing 'owned' rows from 'link' rows and explaining the different consequences. It does not explicitly name alternatives like vault_attach_companion, but the use case is evident from the semantics and sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.